Piezoelectric crystal holder



June 2.1, 1938. R. c. CURTIS y 2,121,340

PIEZOELECTRIC CRYSTAL HOLDER Filed Feb. 17, 1937 l i I DDNDUGTIVE coATlNs l l l 5 1mmgun gulli Wm /9 2/ 5l 5 20 SMS INVENTOR.

ATTORNEY.

BY'VI ZJZLM UNITED STATES PATENT GFFECE PIEzoELEo'rRIo CRYSTAL HOLDER Richard C. Curtis, East Orange, N. J., assigner to Wired Radio, Inc., New York, N. Y., a corporation of Delaware Application February 17, 1937, Serial No. 126,141

6 Claims.

This invention pertains in general to piezoelectricity and specically relates to a piezoelectric crystal holder construction.

The principal object of the invention consists in providing a construction of piezoelectric crystal holder adapted to prevent shifting of the crystal element, while, at the same time, avoid ing unnecessary damping of the crystal vibration.

A further object of the invention comprises providing a. piezoelectric crystal holder construction in which the crystal is clampedl between contact surfaces of reduced areas.

A still further object of the invention com prises providing a piezoelectric crystal holder construction in which a supported crystal is provided with electrode contacts of reduced contacting areas offering a, minimum damping effect to the crystal.

These and other objects will be apparent from the following, reference being had to the accompanying drawing in which like reference numerals designate corresponding parts and in which Fig. 1 is a vertical sectional view of one embodiment of the construction of piezoelectric crystal holder of my invention;

Fig. 2.

The invention contemplates means for mounting a piezoelectric crystal element under optimum conditions so as to facilitate the proper vibration of the crystal in the performance of its function as a stabilizer.

According to the invention,

structural elements are provided for clamping selected points of the ends of the crystal under regulated pressure.

In addition, electrode means are provided for contacting opposed sides of the crystal element with a minimum of force and a minimum of contacting surface.

Referring to the drawing in detail, a piezoelectric crystal element I is mounted edgewise between two prism or V-shaped resilient elements The crystal I is preferably a iiat quartz 2 and 3.

plate ground to the proper dimensions to serve as a frequency controlling element, although other piezoelectric crystal substances such as Rochelle salt may be used, when desired. In accordance with the invention, the crystal I is pro vided with metallic coatings upon opposite sides thereof, for example, as disclosed in U. S. Patent 1,848,630 to Edward O. Hulburt'.

The elements 2 and 3 may be composed oi' rubber or similar material andl are respectively mounted in under-cut slots provided in mounting plates i and 5.

The mounting plate 5 has an annular periph-- eral necked portion which iits into a shielding container Ii, composed of a suitable metal. The mounting plate 5 is provided with upstanding stud members 3 and 9, provided with sleeves Ill and It, carrying the plate Il. The plates 4 and 10 5, parallel with each other, are composed of in* sulating material, and are of circular formation. Nuts l2 and I3 and lock washer lei are provided on the stud member 3, and similar nuts and lock washers are provided on the stud 9, whereby the" 15 plate 4 can be held in desired position with the crystal plate l clamped between the members 2 and 3.

The ends of the stud members 8 and 9 project through holes in the top of the container 5 and are provided with nuts It and Il for securing the container 6 in position. The stud 8 terminates in a plug terminal i9 extending on the opposite side of the plate 5. Two other plug terminals 2U and 2l are mounted in the plate 5, as shown in Fig. 3, and support extension members 22 and 23 within the container 5 and on opposite sides of the crystal element I.

The members 22 and 23 support resilient conn tact members 24 and 25 respectively on opposite 30 sides of the crystal element I. The resilient contact members 24 and 25, of the shape shown, may be composed of a resilient conducting material such as phosphor bronze and exert a gentle force against the crystal l. The ends of the 35 elements 2t and 25 include cone-shaped contacts 26 and 2l which have their points resting adjacent opposite coated faces of the crystal I. 'I'he members 22 and 23 are of conducting material and provide conducting paths from the elements 24 and 25 to the conducting prongs of the plug terminals 20 and 2|. 'I'he prong of the plug tern minal i9 is in electrical contact with stud 8 and through the cover t with stud 9 as shownv and may be connected with ground when the unit as a whole is plugged into a suitable prong receptacle or the like.

The elements 2 and 3 support the crystal plate along its edge with reduced contacting surface for permitting optimum vibration or" the crystal while protecting the crystal from shock. At the same time, the contact members Zl and 25 serve as electrodes for the crystal while, due to the reduced area of the contacting surfaces, avoiding 55 interference with the vibration of the crystal in its frequency controlling operation.

The nodes of vibration of the crystal I are represented by the vertical dotted line H and the horizontal dottedlines V1 and V2 in Fig. l. According to the invention, members 2 and 3 clamp the crystal along the node represented by the dotted line 8 and the contacts 26 and 21 engage the crystal along another node represented by the dotted line V2.

It `will be understood, of course, that crystals with various nodal axes of vibration may be employed, and that the present embodiment of the invention is merely representative of how the electrodes and clamping means are utilized with reference to the nodal axes of a particular type of crystal plate.

'I'he unit as a Whole may be removably insert ed in a suitable socket or receptacle in a irequency controlling organization. Although a preferred form of the crystal holder construction has been disclosed, it will be recognized that various changes and modifications can be made Without departing from the intended scope of the invention. Therefore, no limitation is intended other than as imposed by the scope of the appended claims.

What I claim as new and original and desire to secure by Letters Patent of the United States is:

1. A piezoelectric crystal holder comprising, an insulating mounting plate, a second insulating mounting plate parallel with said first plate, clamping elements carried by said plates for clamping a piezoelectric crystal plate therebe tween along its edges, means for adjusting the relative distance between said plates to regulate the clamping pressure for said crystal, and contacts for resiliently engaging opposite sides of said crystal plate between said mounting plates.

2. The construction in accordance with claim 1 in which said crystal plate is provided With conductive electrode coatings, and in which said contacts comprise flexed strips of resilient ma terial having points thereon engaging opposite surfaces of said coatings.

3. A piezoelectric crystal holder comprising, a shielding container, an insulating plate mounted in one end of said container, a pair of stud members carried by said plate, a second insulating plate mounted on said stud members, resilient Wedge members carried on facing sides of said plate members, a piezoelectric crystal plate having opposed conductive coatings thereon, said plate being mounted between said Wedge members. said Wedge members acting to clamp said piezoelectric crystal element, plug members carried by said rst-mentioned plate for contacting insertion in a socket or receptacle, and flexed contact members mounted onv opposite sides of said crystal plate and having point surfaces contacting said coatings on opposite faces of said crystal plate, said Contact members being electrically connected with different ones of said plug members.

4. The construction in accordance with claim 3 including a plug member in electrical contact with said studs and said container for providing a shielding ground connection.

5. A piezoelectric holder construction comprising, a supporting structure, a piezoelectric element having nodes of vibration, said element having electrode coatings thereon adapted to vibrate With the element, means for clamping said element along its edges substantially along a node of vibration, and contacts for engaging the coatings of said element substantially at nodes of vibration.

6. The crystal holder in accordance with claim 3 in which said Wedges engage said crystal plate along the axis of a node of vibration, and said contact members engage opposite ones of said coatings at nodal points of vibration.

RICHARD C. CURTIS. 

